Características produtivas e nutricionais de gramíneas forrageiras em condições de excesso e déficit hídrico

Abstract

The drought and the flooding can cause reduction in the availability and quality of pastures. The objective was to evaluate the development of three cultivars of Brachiaria brizantha under soil water availability. The experiment was conducted in a greenhouse at the University Campus Rondonópolis. The experimental design was completely randomized in a 3x3 factorial with three cultivars brizantha (cv. Marandu, cv. Piatã and cv. Xaraés)and three water availability, being flooded soil (0 kPa), field capacity (10 kPa, control) and drought (50 kPa), 5 replicates. The soil used was Fluvic, being held fertilization with phosphorus and potassium in doses of 250 and 100 mg dm-3, respectively, and applied 200 mg dm-3 nitrogen applications in four installments. Evaluations were performed at 45, 75 and 105 days of treatment installation. The variables studied were plant height, chlorophyll content, number of leaves, dry weight of leaves, stems, shoots and roots, leaf/stem ratio, relative dry mass of shoots and roots, soil pH and concentration nitrogen. The results were submitted to ANOVA and Tukey test at 5% probability by statistical program SISVAR. The Marandu was the most tolerant to flooding, followed by Piatã. The Xaraés proved to be much more sensitive to drought and the flooding. The highest concentration of nitrogen occurred in the treatment of water deficit. The cultivar with the highest nitrogen concentration was the Piatã, however not the deferred Xaraés.